The present invention relates to a copying machine equipped with a function of copying a double sided document in duplex printing mode.
When copying a double sided document in duplex printing mode (duplex copying), four combinations of copying can be considered according to the direction of binding the document and the direction of binding the output paper. To be more specific, four combinations are as follows: (1) The document is bound in the lateral direction with respect to the image, and output paper is bound in the lateral direction with respect to the print image; (2) the document is bound in the lateral direction with respect to the image, and output paper is bound in the vertical direction with respect to the print image; (3) the document is bound in the vertical direction with respect to the image, and output paper is bound in the lateral direction with respect to the print image; and (4) the document is bound in the vertical direction with respect to the image, and output paper is bound in the vertical direction with respect to the print image; as shown in FIG. 20.
In the case of lateral binding, the images on the front and back are oriented in the same direction. However, in the case of vertical binding, the paper will be placed upside down when the page is turned. Thus, the image of the front must be kept in the state 180 degrees rotated with respect to that of the back.
As described above, the images on the front and back have different orientations, depending on the direction of binding. To meet various combinations of the directions of binding, the following machine has been proposed: A user specifies if the long side or the short of a double-sided document is to be bound, and if the long side or the short side of the output paper is to be bound. Upon receipt of this information, the machine turns the image in the appropriate direction in conformity to the instruction of this information, thereby carrying out printing operation. Based on the aforementioned information received from the user, the orientation of the document and the orientation in which output paper is set, the machine determines the angle of rotation for the first face of the document image and that for the second face to perform duplex printing. (See Patent Document 1, for example).
In addition to the aforementioned proposal, another proposal is concerned with a copying machine wherein a document can be set in a desired direction on the document platen, independently of the type of the document, by setting the type of a document (portrait or landscape type) and the orientation in which the document is set (short edge feed or long edge feed). (See Patent Document 2, for example).    [Patent Document 1] Official Gazette of Japanese Patent 3289497 (Tokkai-Hei 8-6315)    [Patent Document 2] Official Gazette of Japanese Patent Tokkai-2003-145879
In the machine where the bound side of the double-sided document (long or short side) and the bound side of the output paper (long or short side) are to be specified, it is possible to meet various combinations of the directions of binding. However, this method requires these two conditions to be specified every time duplex copying is carried out, and setting operations are complicated. This has been a problem in the prior art.
The present invention has been made to solve the aforementioned problem. The object of the present invention is to provide means for copying a double sided document in duplex printing, capable of enhancing the operability in specifying the direction of binding, while meeting various combinations of the direction of binding the document and that of binding the output paper.